Finland's foreign minister says his country will officially file an application to join NATO as early as next week.

Pekka Haavisto spoke to NHK in the Finnish capital, Helsinki, on Thursday.

Finnish President Sauli Niinisto and Prime Minister Sanna Marin had earlier announced their country would apply for NATO membership without delay.

Haavisto said, "If Parliament comes to the conclusion that we will send an application, then in the middle of next week, we shall do it."

He also said, "Sweden is planning to take similar steps and almost in a similar time table."

Russia issued a warning to Finland, indicating it could take retaliatory steps.

Haavisto said, "We hope that we can keep the border calm and of course, we don't expect anything, but we are prepared for everything." Finland shares a roughly 1,300-kilometer-long border with Russia.

He was asked about the possibility that Russia could take military action before Finland was accepted as a NATO member.

Haavisto said, "It's a risky period for everyone. We have to say that we are not expecting any disturbances, but we have to be ready for those."

He also indicated that Britain and other European countries will strongly support NATO membership for Finland.

Regarding Finland's relations with Russia, Haavisto said, "Russia is a very important neighbor to Finland." He noted the two countries had a positive relationship in the time of former President Boris Yeltsin and former Soviet Union leader Mikhail Gorbachev.

But Haavisto said, "Now it's difficult, because of the Russian attack against Ukraine and Russian attitudes towards the European security architecture."